Conductor terminal for bushings



Sept. 24, 1929. Q AUS'HN 728,952

CONDUCTOR TERMINAL FOR BUSHINGS Filed July 29. 1922 A [AIVENTOR BY {fi EATTORA/EY having an end cap 2 assembled therewit li atentesl t. 2

ARTHUR (Cl. AUSTEN, 15 QEEQ'ASQIGHQR, BY ASSEGNZEENQE,

THE @HEU BRASS oorrirarrr. 632m), A

JER$EY GUN TC! CGBJWRATIUN GE" son assumes Application filed July 28,Serial 130. 523,462

This invention relates to terminal construction for insulator bushingssuch as are used in connection with transformer housings and otherinstallations where insulator bushings are used. The invention has forits object the provision of a terminal construction in which a lowresistant electrical contact is secured, in which the bushing may heremoved or installed Without disturbing the connections within thehousing, which shall exclude moisture from the interior of the hushingand which shall contain other improved features or? construction andoperation which shall appear hereafter.

The invention is exemplified hination and arrangement of parts sl theaccompanying drawing and descrihed in the following specification. andit more particularly pointed out in the appended claims.

In the drawing Fig. l is elevation and part section view showing oneeinhodiment of the present invention.

Fig. 2 is a section on line 2-2 1. As illustrated in the drawing. thenumeral 1 designates a bushing of dielectric rraterial h and providedwith a gasket 3 and cement for forming a tight connection hetween endcap and hushin A conductor 5 extends thru the opening 6 in the bushingand has a square or other angular form 7 secured thereto by brazingsoldering or other ap roved method of attachment The lug 7 orrns acontinuation of the conductor 5 and has its outer end reduced andthreaded as shown at 8,thus forming shoulder 9 at the inner end of thethreaded portion. The endcap 2 has an upwardly extending flange 10provided with an angular opening 11 therethru for receiving the angularportion of the lug 7. Above the opening 11 is a shoulder 12 having anopening for receiving the threaded end 8 of the conductor 5 byproviding'an abutment for the shoulder 9 to limit the upward movement orthe conductor. The nut 13 is threaded on the end 8 the conductor and isscrewed down against the upper surface of the flange it) to clamp theportion 12 thereof hetwecn the shoulder downwardly extending flange 16provided with a yielding gasket it? below the lower oi the tlange andthe top surface of the cap- 2; this will permit the cap it to he screweddown until it is stopped by the hearing and at the same time willcompress the gasket to form a tight joint. the cap is t -us tightened itwill exert an upstress on the threads 8 us in sure close contact betweenthe threaded surfaces on the conductor and terminal or the purpose ofproviding low resista'" trical connection between these parts. furtherinsure close contact between the threaded surfaces, a helical spring 18racy Le interposed hetween the closed end cap upper end of the threadedconduct-or 8. This spring will "exert pressure on the cap conductordrawing upwardly Q on the cap and pressing downwardly on the conductor,thus augmenting the action of abutment surfaces which hold the cap andconductor. The spring 13 will also serve the function of a lock washerfor preventing loosening the cap on the conductor. A. 866GB d spring 19may be interposed between the cap and the nut 13 to assist the spring 18in a sirn way. A conductor lead 20 is provided with a lug 21 secured tothe end a thereotin any approved manner, and having a tapered suriface2Q For engagement with a corresponding surface on a screw clamp or [or23 for connecting the lead the ter nal cap .i very good hearing orelectrical contact can he obtained hetween the upper end of theconductor 8 and the Weather cap ll, as all the stress is taken upbetween the metal parts. This has the advantage, in that the belowwithout being broken.

shrinking of the gasket Will not affect the electrical contact and, inaddition, thermal expansion is not so likely to loosen the joint.

tion is prevented by the squared section 7 which engages ina suitablerecess 11 in the cap. When the weather cap 14 is drawn down tightly thesquared section 7 bears against the shoulder 12 in the cap 2. Thisprevents the lead from being drawn thru the bushing, and when the cap 14is then tightened, pressure is exerted between the cap 2 and the cap 14at the shoulder 15 and between the cap 2 and the lug 7 at 12. If aground joint is provided, this will insure a tight fit, or a gasket mayalso be used.

A preferable method, however, is to install a metal gasket at the point15 or a soft gasket at the point 17. If a tight joint is not necessary,these gaskets may be left out as the cap 14 provides a water shed sothat water cannot drip into the transformer or device upon which thebushing is used. I This form of terminal has the advantage, in that, aflexible conductor 5 may be used. This type of terminal also has theadvantage, in that, it may be applied to practically any bushing towhich the form of cap shown in Q may be attached, as no. specialrecesses are required in the bushing. The cap 23 provides means forconnecting the external lead 20. Electrical contact is insured by thelug 21 and the upper face or the cap at the-surface 25. This may be afiat sur-- face or may be conical to provide increased contact area. Toinsure a good electrical contact, a thin layer of tin or a springingmaterial such as wire gauze, or corrugated disk is used in the joint.Further electrical contact is provided at the surface 22. This contactsurface is'increased by making same conical.

As all stress necessary to make good clectrical contact or to make tightjoint is confined at the top of the bushing a conductor 5 either rigidor solid may be used with a suitable insulating covering which mayextend well up into the bushing and Tlhis-covering reinforces thebushing and tends to prevent electrical discharge Where the conductorleaves the lower end 0 5 the bushing, particularly if the oil level islow or the bushing is installed above oil level. The insulating coveringmay permit the use of a shorter and cheaper bushing, as the covering isvery effective in preventing a discharge to ground or other conductorsfor surges of high magnitude and short duration. If the covering to bebroken at the lower end of the bushing, thi covering would be difficultto insulation.

make and still insure a suflicient degree of With the bushing terminalas shown, a fiber tube or varnished cambric coverings may be used whichare inexpensive and easily installed.

This type'of terminal is generally used where a high degree of tightnessis not essential to prevent leakage of oil or air, but where it ishighly important to keep out rain. This condition is found in generalpractice where the oil level in the transformer or conservator is notabovethe top of the bushing.

I claim:

1'. A dielectric bushing having a metallic fitting secured thereto, aconductor in said bushing, means for clamping said conductor tosaidfitting and a terminal cap for said conductor threaded on the projectingend thereof and bearing against said fitting.

2. A dielectric bushing, a metallic fitting secured to said bushing, aconductor extending through said fitting, a nut for clamping saidconductor to said fitting and a terminal member threaded on saidconductor and bearing against said. fitting so that the force of saidconductor and terminal member caused by tightening said terminal memberwill be transmitted to said fitting.

3. A dielectric bushing having a metallic fitting rigidly fixed to oneend thereof, a conductor having an end portion thereof passing throughan opening in said fitting and having a shoulder engaging said fittingfor limiting outward movement oi' said conductor through said fitting,the minimum diameter of said opening being greater than the maximumdiameter of said end portion to permit passage of said end portionthrough said opening Without relative rotation of said fitting andconductor, a terminal cap threaded on the projecting portion of saidconductor and having bearing against said fitting to draw said conductorto the position to which it is limited by said shoulder, and a gasketinterposed between said terminal cap and litting at a position removedfrom said hearing, and forming a tight joint to close the opening insaid bushin i. A dielectric bushing having metallic fitting securedthereto, a conductor extending freely through said bushing and fitting,means on said fitting for limitin movement of said conductortherethrough, terminal member threaded on said conductor to hold saidconductor against said limiting means and a spring interposed betweensaid conductor and terminal member and exerting opposite forces on saidconductor and terminal member to provide close contact between. theirthreaded surfaces.

5. A dielectric bushing hav'in a metallic fitting secured thereto, aconductor extending loosely through said bushing and fitting, a shoulderfor limiting outward movement of said conductor relative to saidfitting, a

terminal member threaded on said conductor and bearing against saidfitting to exert outward force on said conductor thus insuring closeconnection between the threaded surfaces of said terminal member andconductor, and a spring interposed between said terminal member andconductor for augmenting the force tending to hold said threadedsurfaces in close connection.

6. A dielectric bushing having an opening therethrough, a metallicfitting secured to said dielectric bushing, a conductor having athreaded portion extending through said fitting, a nut for clamping saidconductor to said fitting and a terminal member threaded on saidconductor and bearing against said,

fitting to exert force on said-conductor, said terminal member havingclearance to permit rotation thereof independently of said nut.

7. A dielectric bushing having a metallic fitting secured thereto, aconductor assing through said bushing, means for clamping said conductorto said fitting, a terminal cap threaded on the projecting portion ofsaid conductor and bearing against said fitting, a

spring interposed between said cap and the end of said conductor tendingto move said conductor and terminal cap relative to each other toproduce close contact between their threaded surfaces, and a secondspring interposed between said terminal cap and clamping means foraugmenting the action of said first mentioned spring.

8. A dielectric bushing having a metallic cap secured to the topthereof, a conductor extending through said bushing and having anangular portion fitting a similarly shaped opening in said cap and animperforate cover threaded on said conductor and bearing on said cap toform a seal for said bushing and to provide electric contact with saidconductor, the stress produced by said bearing being entirely confinedto the capand parts mounted thereon.

In testimony whereof I have signed my name to this'specification on this25th day of July, A. D. 1922.

1 ARTHUR O. AUSTIN.

